Objective We tested the hypothesis that percutaneous
myocardial laser may stimulate microvascular growth in
areas surrounding the laser channels.
Methods We conducted a study of 24 domestic pigs, which
underwent percutaneous myocardial laser to left
ventricular myocardium using holmium:YAG laser. The pigs
were sacrificed in groups of four after one day, 3–4 days,
one week, three weeks and six weeks. Frozen sections
from both normal and treated myocardium were prepared
for immunofluorescence microscopy and stained with
antibodies against von Willebrand factor, vascular
endothelial growth factor (VEGF) and Extra Domain-A
cellular fibronectin (ED-AcFN). Microvascular density
(MVD) and vascular area (VA) were determined in sections
stained with antibodies against von Willebrand factor VIII
using a digitised image analysis system. When determined
in laser treated areas, channel core remnants were
excluded from analysis.
Results Within the laser channel remnants and in the
tissue closely surrounding these, expression of VEGF and
ED-AcFN increased significantly after treatment at one,
3–4, and seven days and decreased to normal at three and
six weeks. Expression of ED-AcFN was detected adjacent
to endothelial cells of microvessels. The original laser
channels were rapidly invaded by granulation tissue. There
was no sign of recanalization at any stage during the six
weeks. Morphometric analysis showed no increase in MVD
and VA in the myocardium surrounding the laser
channels.
Conclusion An increase of VEGF and ED-AcFN after
myocardial laser is transient and is not associated with
increase of MVD or VA in myocardium not involving laser
channel remnants. |
